hydrophilic and lubricating contact lenses

Abstract

To provide a hydrophilic and lubricious contact lens.SOLUTION: The present invention provides a contact lens comprising a core lens body and a shell layer. The shell layer covers the core lens body and contains a first polymer containing polyvinyl alcohol, and a second polymer containing polyvinylpyrrolidone. The contact lenses provide appropriate surface smoothness because of the shell layer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a kind of contact lens, and particularly to a contact lens having hydrophilicity and lubricity.

Background Art

[0002] The material of soft contact lenses has been introduced since the 1960s. Due to the soft material, the discomfort that often existed when wearing conventional hard contact lenses (RGP lenses) has been eliminated. Therefore, users who were originally not adapted to hard contact lenses can switch to using soft contact lenses. Therefore, soft contact lenses have become the main choice for current contact lens users.

[0003] Soft contact lenses are softer and more comfortable than hard contact lenses, but still, many users report feeling a foreign object in their eyes when wearing soft contact lenses. This has become the reason for these users to give up using contact lenses. The main cause of this problem is the frictional force on the surface of the contact lens. Therefore, when blinking, the lens moves on the eyeball and rubs against the eyeball, so the user feels that there is something in the eye. To solve this problem, it is necessary to improve the smoothness of the lens surface.

[0004] Many studies have been conducted to obtain a surface lubrication effect by coating the lens surface with polyacrylic acid (PAA). However, PAA is an anionic polymer, which tends to carry a negative charge, and its properties are easily affected by the pH of the tear film. Therefore, irritation may occur during wear. Subsequent research has proposed using a cationic polymer to neutralize the charge of PAA in order to improve the stability of the above-mentioned technology. However, it has become clear that such methods involve significant control costs in the process, and the product cannot stably maintain its lubrication effect during prolonged wear. [Invention details]

[0005] In light of the above-mentioned challenges and technological advancements, the present invention proposes a method that can effectively improve the smoothness of the surface of contact lenses, maintain that effect for a long period of time, and provide a cost-competitive technical solution. [Brief explanation of the drawing]

[0006] [Figure 1] Figure 1 is a schematic cross-sectional view of a contact lens according to one embodiment of the present invention. [Figure 2] Figure 2 is an enlarged schematic view of circle A in Figure 1. [Modes for carrying out the invention]

[0007] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by a person of ordinary skill in the art to which the invention pertains. Generally, the terms and experimental procedures used herein are well known and widely used in the art. These procedures employ prior art methods, such as those provided in the art and various general references. Where a term is provided in the singular form, the inventors have also considered the plural form of that term. The terms and experimental procedures used herein and described below are well known and widely used in the art. Where used throughout this disclosure, unless otherwise stated, the following terms are understood to have the following meanings.

[0008] A dry lens refers to a contact lens that has completed the curing process but has not yet undergone hydration.

[0009] A wet lens refers to a contact lens that has completed the hydration process during the manufacturing process.

[0010] The lens core body refers to the component of a lens formed from the contact lens formulation through curing. The lens core body may be a dry lens or a wet lens. Some of the samples listed in this invention do not have a shell layer.

[0011] The shell layer refers to the surface of the lens core that is formed after the lens core body has been formed and hardened through other processes, but it is not part of the original structure of the lens core body. Furthermore, by forming a stable structure similar to an interpenetrating polymer network structure, the shell layer can stably exist on the surface of the lens core body.

[0012] Interpenetrating polymer networks (IPNs), in general theory, refer to polymer networks that contain two or more polymers, of which at least one polymer is a crosslinked polymer network structure, and where at least two or more polymers partially intersect in terms of size but do not form covalent bonds with each other. For example, if polymer A itself is a crosslinked polymer network structure, and polymer B partially intersects with polymer A, but no covalent bonds are formed between polymer A and polymer B, then polymer A and polymer B can be said to form an interpenetrating polymer network structure. Considering the complexity in the fields of polymers and chemistry, the interpenetrating polymer network structures used in the present invention allow for the occurrence of covalent bonds between different polymers in the formation process and as a result. For example, the disclosed examples of the present invention do not exclude the covalent bonding of a small amount (less than 0.1 wt%) of the first polymer with the polymer of the lens core body. For convenience of expression, the inventors still refer to the partially intersected polymer network formed by the first polymer and the polymer of the lens core body on the surface of the lens core body as an interpenetrating polymer network structure. The polymer structure formed by the entanglement of the first and second polymers within the outer shell layer can be described as a stable structure similar to a reciprocal polymer network structure. In this polymer structure, no clear crosslinking is observed between the polymeric chains of the first polymer itself, nor between the polymeric chains of the second polymer itself. Very strong hydrogen bonds are observed only between the polymeric chains of the first polymer and between the polymeric chains of the first and second polymers, thus forming a stable structure similar to a reciprocal polymer network structure. Therefore, in this invention, in order to get as close as possible to the general theoretical definition, the network structure formed by the first and second polymers in the outer shell layer is not directly called a reciprocal polymer network structure.

[0013] A semi-interpenetrating polymer network (Semi-IPN), in a general theoretical definition, specifically refers to an interpenetrating polymer network structure in which at least one polymer is a linear polymer. The interpenetrating polymer network structure of the present invention includes a semi-interpenetrating polymer network structure.

[0014] A simultaneously interpenetrating polymer network (Simultaneous-IPNs, SINs) is, in a general theoretical definition, a structure that interpenetrates polymers when two or more polymer component units undergo their respective polymerization reactions. For example, in the case of an interpenetrating polymer network structure consisting of polymer A and polymer B, polymer A is formed by the polymerization reaction of monomer a, and polymer B is formed by the polymerization reaction of monomer b. If monomer a and monomer b are mixed and then the mixture is polymerized, the resulting interpenetrating polymer network structure of polymers A and B may be a simultaneously interpenetrating polymer network structure. The interpenetrating polymer network structure according to the present invention does not include, for example, a simultaneously interpenetrating polymer network structure.

[0015] The present invention provides a contact lens comprising a lens core body and a shell layer. The shell layer covers the lens core body. The shell layer comprises at least two types of polymers, a first polymer and a second polymer.

[0016] The first polymer used in the present invention is a polymer containing a polyvinyl alcohol structure. The first polymer may be polyvinyl alcohol, a copolymer of polyvinyl alcohol and polyvinyl acetate (PVA-PVAc copolymer), or a mixture thereof. The first polymer may be crosslinkable or non-crosslinkable. The copolymer of polyvinyl alcohol and polyvinyl acetate may be a block copolymer, an alternate copolymer, a random copolymer, or a graft copolymer. The polyvinyl alcohol may be crosslinkable or non-crosslinkable. The polyvinyl alcohol may be fully hydrolyzed, i.e., fully hydrolyzed polyvinyl alcohol (PVA), or partially hydrolyzed, i.e., partially hydrolyzed polyvinyl alcohol (PVA). Partially hydrolyzed polyvinyl alcohol is preferred. From a classification standpoint, partially hydrolyzed polyvinyl alcohol can also be understood as a type of copolymer of polyvinyl alcohol and polyvinyl acetate (PVA-PVAc copolymer). This is because its polymer segment contains two units: vinyl alcohol and vinyl acetate. Furthermore, fully hydrolyzed polyvinyl alcohol is polyvinyl alcohol whose composition is 100% vinyl alcohol units. Also, partially hydrolyzed polyvinyl alcohol, for example, partially hydrolyzed polyvinyl alcohol with a degree of hydrolysis of 80%, means that it contains 80% vinyl alcohol units and 20% unhydrolyzed vinyl acetate units. In the terminology of this invention, the two terms, partially hydrolyzed polyvinyl alcohol and copolymer of polyvinyl alcohol and polyvinyl acetate, can refer to the same subject and can be used interchangeably.

[0017] In the present invention, partially hydrolyzed polyvinyl alcohol is preferred as the first polymer. The preferred degree of hydrolysis of the partially hydrolyzed polyvinyl alcohol is 70% to 99%, more preferably 80% to 98%, and still more preferably 88% to 95%. The present invention shows that an appropriate degree of hydrolysis of polyvinyl alcohol improves the stability of forming an interpenetrating polymer network structure with the polymer on the surface of the lens core body, and at the same time, it can also improve the stability of the first polymer that forms an interpenetrating polymer network structure with the second polymer in the outer shell layer. The reason why the effect of partially hydrolyzed polyvinyl alcohol is superior to that of completely hydrolyzed polyvinyl alcohol is that the intramolecular hydrogen bonds of completely hydrolyzed polyvinyl alcohol are strong, which makes it difficult for completely hydrolyzed polyvinyl alcohol to penetrate the surface structure of the lens core body (polymer), and thus it is difficult for it to form an interpenetrating polymer network structure with the lens core body (polymer). Similarly, because completely hydrolyzed polyvinyl alcohol has strong intramolecular hydrogen bonds, it is difficult for it to form intermolecular hydrogen bonds with the second polymer containing polyvinylpyrrolidone. Therefore, compared to partially hydrolyzed polyvinyl alcohol, completely hydrolyzed polyvinyl alcohol is less likely to form a similar interpenetrating polymer network structure with the second polymer.

[0018] The preferred range for the molecular weight (Mw) of the first polymer is 5,000 to 300,000 Da, a more preferred range is 10,000 to 200,000 Da, an even more preferred range is 15,000 to 150,000 Da, and the most preferred range is 25,000 to 100,000 Da.

[0019] The second polymer used in this invention is a polymer containing a polyvinyl pyrrolidone structure. The second polymer may be polyvinyl pyrrolidone, a copolymer containing polyvinyl pyrrolidone, or a mixture thereof. The second polymer may be crosslinkable or non-crosslinkable. The copolymer containing polyvinyl pyrrolidone may be a copolymer of vinylpyrrolidone and dimethylaminoethyl methacrylate {(vinylpyrrolidone)-co-(dimethylaminoethylmethacrylate)}, and specific examples include Copolymer 845, Copolymer 937, and Copolymer 958 sold by Ashland Inc. The molecular weight of the vinylpyrrolidone-dimethylaminoethyl methacrylate copolymer is, for example, 100,000 Da or more.

[0020] The preferred molecular weight (Mw) of the second polymer is 8,000 Da or higher, more preferably 100,000 Da or higher, even more preferably 160,000 Da or higher, and most preferably 360,000 Da or higher. The molecular weight range of the second polymer allows for the formation of an effective outer shell layer. If the molecular weight of the second polymer is insufficient, it is difficult to form an effective outer shell layer together with the first polymer. This is thought to be because, even if a similar interpenetrating polymer network structure can be formed together with the first polymer when the molecular weight of the second polymer is small, migration is more likely to occur within the structure due to the small molecular weight of the second polymer, resulting in insufficient stability of the outer shell layer.

[0021] At the boundary between the lens core body and the outer shell layer, the polymer structures of the first polymer and the lens core body form an interpenetrating polymer network structure. In most of the outer shell layer, a stable structure similar to the interpenetrating polymer network structure is formed between the first polymer and the second polymer.

[0022] At the boundary between the lens core body and the outer shell layer, the polymer structure of the first polymer and the polymer structure of the lens core body form an interpenetrating polymer network structure. Within this interpenetrating polymer network structure, some of the first polymers are freely movable polymers, and stable bonds are formed between other parts of the first polymers, and these bonds stabilize the interpenetrating polymer network structure. The formation of these bonds mainly originates from the contact lens sterilization (autoclave) process, which generates stable hydrogen bonds between polyvinyl alcohols due to high temperature and high pressure. Therefore, the part of the outer shell layer that is in contact with the lens core body is mainly composed of the first polymer, and the part of the outer shell layer that is away from the lens core body is mainly composed of the second polymer. In most of the outer shell layer, a stable structure similar to an interpenetrating polymer network structure is formed between the first polymer and the second polymer. Within this structure, some of the first polymers are freely movable polymers, some of the second polymers are also freely movable polymers, and stable bonds are formed between some of the first polymers, and these bonds stabilize the similar interpenetrating polymer network structure. The formation of the aforementioned bonds primarily originates from the contact lens sterilization process, resulting in the creation of stable hydrogen bonds between polyvinyl alcohol molecules. Simultaneously, stable hydrogen bonds can also be formed between polyvinyl alcohol and polyvinylpyrrolidone, mainly due to the hydroxyl groups of polyvinyl alcohol and the oxygen atoms of polyvinylpyrrolidone. Therefore, the overall structure of the outer layer becomes relatively stable, maintaining comfort for the wearer.

[0023] To elaborate further, controlling the proportion of vinyl acetate in the first polymer (i.e., the degree of hydrolysis of partially hydrolyzed polyvinyl alcohol) can significantly affect the formation effect of the outer shell layer. Because the polyvinyl alcohol structure itself has strong crystallinity, if the crystallinity of the first polymer is too strong, the first polymer cannot effectively penetrate the surface structure of the lens core before forming the outer shell layer, and the first polymer cannot form a semi-interpenetrating polymer network structure together with the surface structure of the lens core. As a result, a stable interpenetrating polymer network structure cannot be formed in the subsequent sterilization process. Similarly, if the crystallinity of the first polymer is too strong, the oxygen atoms of polyvinylpyrrolidone in the second polymer will have difficulty forming hydrogen bonds with the hydroxyl groups of polyvinyl alcohol in the first polymer. This makes it difficult for sufficient entanglement to occur between the first and second polymers, affecting the effect of the first and second polymers in forming a similar interpenetrating polymer network structure, and consequently affecting the stability of the outer shell layer. Furthermore, a portion of the vinyl acetate in the first polymer can react with some of the vinyl alcohol during sterilization, forming an action similar to a cross-linking reaction, which can further stabilize the structure of the outer shell layer and simultaneously help the outer shell layer fix and cover the lens core body.

[0024] One of the key factors in the formation of the stable outer shell layer referred to in this invention is that the first polymer can form a mutually penetrating polymer network structure with the lens core body, and at the same time, the first polymer can also form a mutually penetrating polymer network structure with the second polymer. The sterilization process is a key factor in the formation of this stable mutually penetrating polymer network structure. The high temperature and pressure during sterilization generate stable hydrogen bonds between the polyvinyl alcohols in the first polymer. Simultaneously, some of the vinyl acetate in the first polymer can react with some of the vinyl alcohols during sterilization, forming an action similar to a crosslinking reaction. This transforms the semi-mutually penetrating polymer network structure originally formed by the surface structure of the first polymer and the lens core body into a more stable mutually penetrating polymer network structure. Similarly, while the first and second polymers in the outer shell layer initially only exhibited simple physical adsorption and minor entanglement, the high temperature and pressure during sterilization induce the formation of hydrogen bonds and crosslinking-like reactions between the first polymers, as well as strengthening the hydrogen bonds between the first and second polymers, further enhancing the strength of the entanglement. Therefore, the sterilization process not only helps the outer shell layer stably coat the lens core body, but also helps to enhance the stability of the outer shell layer itself.

[0025] The first polymer used in the present invention does not necessarily have to contain positively charged polymer segments (cationic polymeric segments) and does not necessarily have to contain negatively charged polymer segments (anionic polymeric segments).

[0026] The first polymer used in the present invention may contain a positively charged polymer segment, provided that the positively charged polymer segment shall not have an inhibitory effect on the formation of an interpenetrating polymer network structure between the first polymer and the polymer of the lens core body. Also, it shall not have an inhibitory effect on the formation of stable entanglement between the first polymer and the second polymer. Similarly, the first polymer used in the present invention may contain a negatively charged polymer segment, provided that the negatively charged polymer segment shall not have an inhibitory effect on the formation of an interpenetrating polymer network structure between the first polymer and the polymer of the lens core body. Also, it shall not have an inhibitory effect on the formation of stable entanglement between the first polymer and the second polymer.

[0027] The second polymer used in the present invention may not contain a cationic polymeric segment and may not contain an anionic polymeric segment.

[0028] The second polymer used in the present invention may contain a positively charged polymer segment, provided that the positively charged polymer segment shall not have an inhibitory effect on the formation of an interpenetrating polymer network structure between the first polymer and the polymer of the lens core body; also, it shall not have an inhibitory effect on the formation of stable entanglement between the second polymer and the first polymer. Similarly, the second polymer used in the present invention may contain a negatively charged polymer segment, provided that the negatively charged polymer segment shall not have an inhibitory effect on the formation of an interpenetrating polymer network structure between the first polymer and the polymer of the lens core body; also, it shall not have an inhibitory effect on the formation of stable entanglement between the second polymer and the first polymer.

[0029] To facilitate reader understanding, a detailed theoretical explanation is provided here regarding the structural relationship and principle between the first polymer and the lens core body, as well as the structural relationship and principle between the first polymer and the second polymer. However, this theoretical explanation should not be derived or interpreted in a way that limits the scope of the patent rights of this invention.

[0030] As shown in the examples, the lens core of the contact lens provided by the present invention is mainly composed of HEMA (2-hydroxyethyl methacrylate), meaning that the HEMA content may be 85% or more, or 90% or more, or even 95% or more. The composition and percentage calculations described herein do not include the diluent. This type of contact lens is generally called a hydrogel contact lens.

[0031] As shown in the examples, the lens core of the contact lens provided by the present invention may be a contact lens containing a silicone-containing component. The silicone-containing component may be a silicone monomer or a silicone macromer, and may also contain a silicone-containing crosslinker. This type of contact lens is generally called a silicone hydrogel contact lens.

[0032] The present invention now provides a detailed reference to embodiments of the present invention, describing one or more such embodiments. Each embodiment is provided for illustrative purposes only, and not to limit the present invention. In practice, it will be apparent to a person with ordinary skill in the art to which the present invention belongs that various modifications and changes can be made to the present invention without departing from the spirit of the invention. For example, features disclosed or described as part of one embodiment can be used in another embodiment to generate a new embodiment. Thus, the present invention is intended to include such modifications and changes that fall within the scope of the appended claims and their equivalents. Other objects, features, and directions of the present invention are disclosed in the following detailed description or will become apparent from the following detailed description. A person with ordinary skill in the art to which the present invention belongs should understand that the present discussion is merely a description of exemplary embodiments and is not intended to limit broader aspects of the present invention.

[0033] Figure 1 is a schematic cross-sectional view of a contact lens in one embodiment of the present invention. Figure 2 is an enlarged schematic view of circle A in Figure 1. Referring to Figures 1 and 2, the contact lens 100 in one embodiment of the present invention includes a lens core body 110 and an outer shell layer 120, the outer shell layer 120 covering the lens core body 110. The outer shell layer 120 includes a first polymer 121 and a second polymer 122, the first polymer 121 containing polyvinyl alcohol and the second polymer 122 containing polyvinylpyrrolidone. The first polymer 121 covers, for example, the lens core body 110, and the second polymer 122 covers, for example, the first polymer 121.

[0034] Abbreviations and descriptions of the compounds used in lens formulations: TIFF0007864159000001.tif83160

[0035] Sample 1-1 (EX1-1): A Hydrogel-1 dry lens was prepared, with the lens composition shown in Table 1. The process from lens compounding to dry lens production is well-known in this art, and a mold-based manufacturing method can be selected. For the contact lens curing method, either photocuring or thermal curing can be selected, and photocuring was selected for this sample. The dry lens was hydrated in hot water at 70±5 degrees Celsius (reverse osmosis water (RO water) was used) for 60 minutes to wash away the monomers, crosslinking agents, initiators, and fillers remaining from the curing reaction to obtain a wet lens. The obtained wet lens was immersed in an aqueous solution containing 0.2 g / L of PVA-PVAc copolymer for 120 minutes. The purpose of this immersion process is to allow the PVA-PVAc copolymer to penetrate the surface of the lens core by mass transfer. The PVA-PVAc copolymer used here is designated PVA-PVAc-1, with a molecular weight of 31,000 Da and containing 88% PVA, i.e., a partially hydrolyzed polyvinyl alcohol with a degree of hydrolysis of 88%. After completing these steps, the wet lens was removed from the aqueous solution of the PVA-PVAc copolymer and placed in a polypropylene (PP) cup, and Buffer-1 was added dropwise to the PP cup. The level of the buffer solution must be higher than the wet lens, ensuring that all of the buffer solution completely covers the wet lens. After completion, the aluminum foil and PP cup were sealed using a heat seal method and sterilized in an autoclave. The sterilization conditions were to heat the temperature to 122 degrees Celsius and maintain it at 122 degrees Celsius and 2 atmospheres for 30 minutes. As a result, a contact lens was obtained in which the lens core body has a water content of approximately 38% and is mainly composed of HEMA, the outer shell layer is mainly composed of PVA-PVAc copolymer and PVP, and the lens core body and PVP are bonded by the PVA-PVAc copolymer.Approximately 12 hours after the wet lenses came into contact with the buffer (including the sterilization process), the aluminum foil was opened, the contact lenses were removed, and they were placed in a standard buffer solution to equilibrate. 10 ml of standard buffer solution was used per contact lens, and the buffer was replaced every hour. This process was repeated three times, after which the smoothness of the contact lens surface was evaluated. The mixing ratios of Buffer-1 and Standard buffer are shown in Table 2.

[0036] [Table 1]

[0037] Footnote: Diluents in Table 1 (including Glycerin, 1-Hexanol, and DEGBE) are not included in the calculation of the lens's total composition (SUM). The SUM is added as the denominator to 100%. For example, the composition of Hydrogel-1 is HEMA 98.5g, MAA 0.1g, EGDMA 1.0g, and Irgracure819 0.4g, with a total weight of 100g. In this case, 15.0g of Glycerin is added separately as a diluent.

[0038] [Table 2]

[0039] Footnote: The numerical units in Table 2 are grams (g). PVP360K is PVP with a molecular weight of 360,000 Da, PVP8K is PVP with a molecular weight of 8,000 Da, PVA-PVAc-1 is a PVA-PVAc copolymer with a molecular weight of 31,000 Da in which PVA accounts for 88% of the total, PVA-PVAc-2 is a PVA-PVAc copolymer with a molecular weight of 205,000 Da in which PVA accounts for 88% of the total, and PVA-PVAc-3 is a PVA-PVAc copolymer with a molecular weight of 27,000 Da in which PVA accounts for 98% of the total.

[0040] Sample 1-2 (EX1-2): Prepared using the same method as Sample 1-1, but instead of heat-sealing the aluminum foil and PP cup and then sterilizing it in an autoclave, the wet lens was simply immersed in Buffer-1 within the heat-sealed aluminum foil PP cup. Approximately 12 hours after the wet lens began contact with the buffer (including the sterilization process), the aluminum foil was opened, the contact lens was removed, and it was placed in a standard buffer solution to equilibrate. 10 ml of standard buffer solution was used per contact lens, and the buffer was changed every hour. This was repeated three times, and then the smoothness of the contact lens surface was measured.

[0041] Sample 2-1 (EX2-1): A Hydrogel-2 dry lens was manufactured, and the lens composition is shown in Table 1. The process from lens compounding to the manufacture of the dry lens is well known in this art, and a mold-based manufacturing method can be selected. For the hardening method of the contact lens, either photocuring or thermal curing can be selected, and photocuring was selected for this sample. The purpose of immersing the dry lens in a 0.5 wt% sodium carbonate aqueous solution for 20 minutes is to rapidly ionize the MAA in the dry lens, causing the dry lens to expand and improving cleaning efficiency. After that, it is hydrated with RO water at room temperature (20-30 degrees Celsius) for 40 minutes to wash away the monomers, crosslinking agents, initiators, and fillers remaining from the hardening reaction from the dry lens to obtain a wet lens. The obtained wet lens is immersed in an aqueous solution containing 0.2 g / L of PVA-PVAc copolymer for 120 minutes. The purpose of this immersion process is to allow the PVA-PVAc copolymer to penetrate the surface of the lens core by mass transfer. The PVA-PVAc copolymer used here is designated PVA-PVAc-1, with a molecular weight of 31,000 Da and containing 88% PVA, i.e., a partially hydrolyzed polyvinyl alcohol with a degree of hydrolysis of 88%. After completing these steps, the wet lens was removed from the aqueous solution of the PVA-PVAc copolymer and placed in a PP cup, and Buffer-1 was added dropwise to the PP cup. The level of the buffer solution must be higher than the wet lens, ensuring that all of the buffer solution completely covers the wet lens. After completion, the aluminum foil and PP cup were sealed using a heat seal method and sterilized in an autoclave. The sterilization conditions were to heat the temperature to 122 degrees Celsius and maintain it at 122 degrees Celsius and 2 atmospheres for 30 minutes. As a result, a contact lens was obtained in which the lens core body has a water content of approximately 55% and is mainly composed of HEMA, the outer shell layer is mainly composed of PVA-PVAc copolymer and PVP, and the lens core body and PVP are bonded by the PVA-PVAc copolymer.Approximately 12 hours after the wet lenses came into contact with the buffer (including the sterilization process), the aluminum foil was opened, the contact lenses were removed, and they were placed in a standard buffer solution to equilibrate. 10 ml of standard buffer solution was used per contact lens, with the buffer replaced every hour. This process was repeated three times, after which the smoothness of the contact lens surface was evaluated.

[0042] Sample 2-2 (EX2-2): Prepared using the same method as Sample 2-1, but instead of heat-sealing the aluminum foil and PP cup and then sterilizing it in an autoclave, the wet lens was simply immersed in Buffer-1 within the heat-sealed aluminum foil PP cup. Approximately 12 hours after the wet lens began contact with the buffer (including the sterilization process), the aluminum foil was opened, the contact lens was removed, and it was placed in a standard buffer solution to equilibrate. 10 ml of standard buffer solution was used per contact lens, and the buffer was changed every hour. This was repeated three times, and then the smoothness of the contact lens surface was evaluated.

[0043] Sample 3-1 (EX3-1): A dry lens made of silicone hydrogel was manufactured, and the lens composition is shown in Table 1. The process from lens compounding to the manufacture of the dry lens is a well-known technique in this art, and a manufacturing method using a mold can be selected. For the curing method of the contact lens, either photocuring or thermal curing can be selected, and photocuring was selected for this sample. First, the dry lens was immersed in an aqueous solution containing 50 wt% isopropyl alcohol (isopropanol, IPA) for 60 minutes. This rapidly expands the dry lens and improves cleaning efficiency. Furthermore, by utilizing the principle that IPA has a high affinity for the silicone-containing components TRIS and MPDMS, any TRIS and MPDMS that did not react completely during the curing stage, as well as any remaining other monomers, crosslinking agents, initiators, and fillers, were thoroughly washed away. Subsequently, a wet lens was obtained by immersing the lens in RO water at room temperature (20-30 degrees Celsius) four times for 30 minutes each time, replacing the RO water with fresh water each time, and completely rinsing off the IPA. The resulting wet lens was immersed for 120 minutes in an aqueous solution containing 0.2 g / L of PVA-PVAc copolymer. The purpose of this immersion process is to allow the PVA-PVAc copolymer to permeate the surface of the lens core by mass transfer. The PVA-PVAc copolymer used here is PVA-PVAc-1, with a molecular weight of 31,000 Da, and is a PVA-PVAc copolymer in which PVA accounts for 88% of the total, i.e., a partially hydrolyzed polyvinyl alcohol with a degree of hydrolysis of 88%. After completing these steps, the wet lens was removed from the aqueous solution of PVA-PVAc copolymer and placed in a PP cup, and Buffer-1 was added dropwise to the PP cup. The level of the buffer solution must be higher than the wet lens, and all of the buffer solution must completely cover the wet lens. After completion, the aluminum foil and PP cup were sealed using a heat seal method and sterilized in an autoclave. The sterilization conditions involve continuously heating to 122 degrees Celsius, maintaining that temperature at 122 degrees Celsius and 2 atmospheres of pressure for 30 minutes.As a result, a contact lens was obtained in which the lens core body was made of silicone hydrogel, the outer shell layer was mainly composed of PVA-PVAc copolymer and PVP, and the lens core body and PVP were bonded by the PVA-PVAc copolymer. Approximately 12 hours after the wet lens came into contact with the buffer (including the sterilization process), the aluminum foil was opened, the contact lens was removed and placed in a standard buffer solution to equilibrate, and 10 ml of standard buffer solution was used per contact lens, with the buffer solution being changed every hour, and this was repeated three times, after which the smoothness of the contact lens surface was evaluated.

[0044] Sample 3-2 (EX3-2): Prepared using the same method as Sample 3-1, but instead of heat-sealing the aluminum foil and PP cup and then sterilizing it in an autoclave, the wet lens was simply immersed in Buffer-1 within the heat-sealed aluminum foil PP cup. Approximately 12 hours after the wet lens began contact with the buffer (including the sterilization process), the aluminum foil was opened, the contact lens was removed, and it was placed in a standard buffer solution to equilibrate. 10 ml of standard buffer solution was used per contact lens, and the buffer was changed every hour. This was repeated three times, and then the smoothness of the contact lens surface was evaluated.

[0045] Sample 4-1 (EX4-1): A Hydrogel-2 dry lens was prepared, with the lens composition shown in Table 1. The process from lens formulation to dry lens production is well-known in this art, and a mold-based manufacturing method can be selected. For the contact lens curing method, either photocuring or thermal curing can be selected, and photocuring was selected for this sample. The reason for immersing the dry lens in a 0.5 wt% sodium carbonate aqueous solution for 20 minutes is to rapidly ionize the MAA in the dry lens, causing it to expand and improving cleaning efficiency. Subsequently, it is hydrated with RO water at room temperature (20-30 degrees Celsius) for 40 minutes to wash away any monomers, crosslinking agents, initiators, and fillers remaining from the curing reaction to obtain a wet lens. The obtained wet lens was placed in a pp cup, and Buffer-3 was added dropwise to the pp cup. The level of the buffer must be higher than the wet lens, ensuring that all of the buffer completely covers the wet lens. After completion, the aluminum foil and PP cup were sealed using a heat-sealing method and sterilized in an autoclave. The sterilization conditions were to continuously heat the temperature to 122 degrees Celsius and maintain 122 degrees Celsius at 2 atmospheres for 30 minutes. As a result, a contact lens was obtained in which the lens core body had a water content of approximately 55% and was mainly composed of HEMA, the outer shell layer was mainly composed of PVA-PVAc copolymer and PVP, and the lens core body and PVP were bonded by the PVA-PVAc copolymer. Approximately 12 hours after the wet lens came into contact with the buffer (including the sterilization process), the aluminum foil was opened, the contact lens was removed and placed in a standard buffer solution to equilibrate, and 10 ml of standard buffer solution was used per contact lens, with the buffer solution being changed every hour, and this was repeated three times, after which the smoothness of the contact lens surface was evaluated. The mixing ratio of Buffer-3 is listed in Table 2.

[0046] Sample 4-2 (EX4-2): A Hydrogel-2 dry lens was manufactured, and the lens composition is shown in Table 1. The process from lens compounding to the manufacture of the dry lens is well known in this art, and a mold-based manufacturing method can be selected. For the hardening method of the contact lens, either photocuring or thermal curing can be selected, and photocuring was selected for this sample. The reason for immersing the dry lens in a 0.5 wt% sodium carbonate aqueous solution for 20 minutes is to rapidly ionize the MAA in the dry lens, causing the dry lens to expand and improving cleaning efficiency. After that, it is hydrated with RO water at room temperature (20-30 degrees Celsius) for 40 minutes to wash away the monomers, crosslinking agents, initiators, and fillers remaining from the hardening reaction from the dry lens to obtain a wet lens. The obtained wet lens was immersed in a 0.6 g / L PVP aqueous solution for 120 minutes. The purpose of this immersion process is to allow PVP to penetrate the surface of the lens core body by mass transfer. The PVP used here is PVP360, which has a molecular weight of 360,000 Da. After completing these steps, the wet lens was removed from the PVP aqueous solution and placed in a PP cup, and Buffer-2 was added dropwise to the PP cup. The level of the buffer solution must be higher than the wet lens, ensuring that all of the buffer solution completely covers the wet lens. After completion, the aluminum foil and PP cup were sealed using a heat seal method and sterilized in an autoclave. The sterilization conditions were to heat the temperature to 122 degrees Celsius and maintain it at 122 degrees Celsius and 2 atmospheres for 30 minutes. Approximately 12 hours after the wet lens came into contact with the buffer solution (including the sterilization process), the aluminum foil was opened, the contact lens was removed and placed in a standard buffer solution to equilibrate. 10 ml of standard buffer solution was used per contact lens, with the buffer solution changed every hour, and this was repeated three times. After that, the smoothness of the contact lens surface was evaluated. The mixing ratio of Buffer-2 is shown in Table 2.

[0047] Sample 5-1 (EX5-1): Prepared using the same method as Sample 4-1, but with the PVP in the buffer replaced by Copolymer 845. Approximately 12 hours after the wet lens began contact with the buffer (including the sterilization process), the aluminum foil was opened, the contact lens was removed, and it was placed in a standard buffer solution to equilibrate. 10 ml of standard buffer solution was used per contact lens, and the buffer was changed every hour. This was repeated three times, after which the smoothness of the contact lens surface was evaluated.

[0048] Sample 5-2 (EX5-2): A Hydrogel-2 dry lens was prepared, with the lens composition shown in Table 1. The process from lens formulation to dry lens production is well-known in this art, and a mold-based manufacturing method can be selected. For the contact lens curing method, either photocuring or thermal curing can be selected, and photocuring was selected for this sample. The reason for immersing the dry lens in a 0.5 wt% sodium carbonate aqueous solution for 20 minutes is to rapidly ionize the MAA in the dry lens, causing it to expand and improving cleaning efficiency. Subsequently, it is hydrated with RO water at room temperature (20-30 degrees Celsius) for 40 minutes to wash away any monomers, crosslinking agents, initiators, and fillers remaining from the curing reaction to obtain a wet lens. The obtained wet lens was placed in a pp cup, and Buffer-2 was added dropwise to the pp cup. The level of the buffer must be higher than the wet lens, ensuring that all of the buffer completely covers the wet lens. After completion, the aluminum foil and PP cup were sealed using a heat seal method and sterilized in an autoclave. The sterilization conditions were to continuously heat the temperature to 122 degrees Celsius and maintain 122 degrees Celsius and 2 atmospheres for 30 minutes. After the sterilization was complete, the aluminum foil was opened, the contact lens was removed and placed in a new PP cup, and Buffer-1 was added to the PP cup. The level of the buffer solution must be higher than the wet lens, and all of the buffer solution must completely cover the wet lens. After completion, the aluminum foil and PP cup were sealed using a heat seal method and sterilized a second time in an autoclave. The sterilization conditions were to continuously heat the temperature to 122 degrees Celsius and maintain 122 degrees Celsius and 2 atmospheres for 30 minutes. After completion, the aluminum foil was opened, the contact lenses were removed and placed in a standard buffer solution to equilibrate. 10 ml of the standard buffer solution was used per contact lens, with the buffer replaced every hour. This process was repeated three times, after which the smoothness of the contact lens surface was evaluated.

[0049] Sample 6-1 (EX6-1): Prepared using the same method as Sample 4-1, but with the substitution of Buffer-3 with Buffer-4. The mixing ratio of Buffer-4 is shown in Table 2. After sterilization was complete, approximately 12 hours (including the sterilization process) had elapsed since the wet lens began contact with the buffer. Then, the aluminum foil was opened, the contact lens was removed, and it was placed in a standard buffer solution to equilibrate. 10 ml of standard buffer solution was used per contact lens, and the buffer was changed every hour. This was repeated three times, after which the smoothness of the contact lens surface was evaluated.

[0050] Sample 7-1 (EX7-1): Prepared using the same method as Sample 4-1, but with the substitution of Buffer-3 with Buffer-5. The mixing ratio of Buffer-5 is shown in Table 2. After sterilization was complete, approximately 12 hours (including the sterilization process) had elapsed since the wet lens began contact with the buffer. Then, the aluminum foil was opened, the contact lens was removed, and it was placed in a standard buffer solution to equilibrate. 10 ml of standard buffer solution was used per contact lens, and the buffer was changed every hour. This was repeated three times, after which the smoothness of the contact lens surface was evaluated.

[0051] Sample 8-1 (EX8-1): Prepared using the same method as Sample 4-1, but with the substitution of Buffer-3 with Buffer-6. The mixing ratio of Buffer-6 is shown in Table 2. After sterilization was complete, approximately 12 hours (including the sterilization process) had elapsed since the wet lens began contact with the buffer. Then, the aluminum foil was opened, the contact lens was removed, and it was placed in a standard buffer solution to equilibrate. 10 ml of standard buffer solution was used per contact lens, and the buffer was changed every hour. This was repeated three times, after which the smoothness of the contact lens surface was evaluated.

[0052] Sample 9-1 (EX9-1): A Hydrogel-2 dry lens was prepared, and the lens composition is shown in Table 1. The process from lens formulation to dry lens production is well known in this art, and a mold-based manufacturing method can be selected. For the hardening method of the contact lens, photocuring or thermal curing can be selected, and photocuring was selected for this sample. The reason for immersing the dry lens in a 0.5 wt% sodium carbonate aqueous solution for 20 minutes is to rapidly ionize the MAA in the dry lens, causing the dry lens to expand and improving cleaning efficiency. After that, it is hydrated with RO water at room temperature (20-30 degrees Celsius) for 40 minutes to wash away the monomers, crosslinking agents, initiators, and fillers remaining from the hardening reaction from the dry lens to obtain a wet lens. The obtained wet lens was immersed in a 0.2 g / L PVA (molecular weight 145,000 Da, degree of hydrolysis 99%) aqueous solution and heated at 70 ± 5 degrees Celsius for 120 minutes. Subsequently, the wet lens was immersed in a 0.6 g / L aqueous solution of PVP (molecular weight 360,000 Da) and heated at 70 ± 5 degrees Celsius for 120 minutes. The resulting wet lens was placed in a PP cup, and a standard buffer salt solution was added dropwise to the PP cup. The buffer solution level must be higher than the wet lens, ensuring that all of the buffer solution completely covers the wet lens. After completion, the aluminum foil and PP cup were sealed using a heat seal method and then sterilized in an autoclave. The sterilization conditions were to heat the temperature to 122 degrees Celsius and maintain it at 122 degrees Celsius and 2 atmospheres for 30 minutes. Approximately 12 hours after the wet lenses came into contact with the buffer (including the sterilization process), the aluminum foil was opened, the contact lenses were removed, and they were placed in a standard buffer solution to equilibrate. 10 ml of the standard buffer solution was used per contact lens, with the buffer replaced every hour, and this process was repeated three times. After that, the smoothness of the contact lens surface was evaluated. The mixing ratios of the standard buffer solution are shown in Table 2.

[0053] Sample 6-2 (EX6-2): Prepared using the same method as Sample 9-1, but instead of heat-sealing the aluminum foil and PP cup and then sterilizing it in an autoclave, the wet lens was simply immersed in a standard buffer solution within the heat-sealed aluminum foil PP cup. Approximately 12 hours after the wet lens began contact with the buffer solution (including the sterilization process), the aluminum foil was opened, the contact lens was removed, and it was placed in a standard buffer solution to equilibrate. 10 ml of standard buffer solution was used per contact lens, and the buffer solution was changed every hour. This was repeated three times, and then the smoothness of the contact lens surface was evaluated.

[0054] Sample 7-2 (EX7-2): Prepared using the same method as Sample 4-1, but with the substitution of Buffer-3 with Buffer-1. The mixing ratio of Buffer-1 is shown in Table 2. After sterilization was complete, approximately 12 hours (including the sterilization process) had elapsed since the wet lens began contact with the buffer. Then, the aluminum foil was opened, the contact lens was removed, and it was placed in a standard buffer solution to equilibrate. 10 ml of standard buffer solution was used per contact lens, and the buffer was changed every hour. This was repeated three times, after which the smoothness of the contact lens surface was evaluated.

[0055] Sample 8-2 (EX8-2): Prepared using the same method as Sample 7-2, but before evaluating the smoothness of the contact lens surface, the aluminum foil was opened, the contact lens was removed, and it was placed in a standard buffer solution to equilibrate. 10 ml of standard buffer solution was used per contact lens, and the buffer was changed every hour. This was repeated three times, after which the smoothness of the contact lens surface was evaluated.

[0056] Sample 9-2 (EX9-2): Prepared using the same method as Sample 4-1, but with the substitution of Buffer-3 with Buffer-2. The mixing ratio of Buffer-2 is shown in Table 2. After sterilization was complete, approximately 12 hours (including the sterilization process) had elapsed since the wet lens began contact with the buffer. Then, the aluminum foil was opened, the contact lens was removed, and it was placed in a standard buffer solution to equilibrate. 10 ml of standard buffer solution was used per contact lens, and the buffer was changed every hour. This was repeated three times, after which the smoothness of the contact lens surface was evaluated.

[0057] The surface lubricity score of contact lenses is evaluated. The surface lubricity of contact lenses is evaluated on a scale of 1 to 4. A higher score indicates a smoother contact lens. A score of 1 indicates a contact lens that is not smooth at all, as felt when rubbed with the hand. A score of 2 indicates a contact lens that is slightly smooth, as felt when rubbed with the hand, and is equivalent in evaluation to the commercially available contact lens product Acuvue Oasys 1 day. A score of 3 indicates a contact lens that is moderately smooth. A score of 4 indicates a contact lens that is very smooth, and is equivalent in evaluation to the commercially available contact lens product Dailies Total 1. It should be explained that while some contact lens users rate the wearing comfort of Dailies Total 1 as very good, the contact lenses are too slippery, making it very difficult to remove them from the eye after use, which affects their willingness to continue using that brand of contact lens. Therefore, a higher smoothness score is not always better. In the evaluation of this invention, the optimal smoothness score is 3.

[0058] Surface Smoothness Evaluation Test Method: Five subjects are selected, and each subject simultaneously rubs two products, Acuvue Oasys 1 day and Dailies Total 1. The smoothness of the Acuvue Oasys 1 day is rated on a scale of 2, and the smoothness of the Dailies Total 1 is rated on a scale of 4. If four out of the five subjects rate the smoothness of the test sample as clearly lower than that of Acuvue Oasys 1 day, the smoothness score of the test sample is 1. If three subjects rate the smoothness of the test sample as lower than that of Acuvue Oasys 1 day, and two subjects rate the difference as unclear, the score is 1-2. If four or more subjects judge the smoothness of the test sample to be equivalent to that of Acuvue Oasys 1 day, the score is 2. If three or more people rate the smoothness of the sample being tested as clearly superior to that of Acuvue Oasys 1 day, and two more rate it as equivalent to that of Acuvue Oasys 1 day, the score will be 2-3 points. If four or more people rate the smoothness of the sample being tested as clearly superior to that of Acuvue Oasys 1 day, the score will be 3 points.

[0059] Table 3 shows the evaluation of surface smoothness in this sample.

[0060] [Table 3]

[0061] The data in Table 3 shows that the technical features proposed by the present invention (samples EX1-1, 2-1, 3-1, 4-1, 5-1, 6-1, 7-1, 8-1, and 9-1) effectively improve surface smoothness and allow for control within an appropriate range. The main difference between sample 1-1 (EX1-1) and sample 1-2 (EX1-2) is the presence or absence of sterilization. Sample 1-1, which underwent sterilization, has a higher surface smoothness score of 3. Similarly, the surface smoothness score of sample 2-1 (EX2-1) is higher than that of sample 2-2 (EX2-2). The surface smoothness score of sample 3-1 (EX3-1) is also higher than that of sample 3-2 (EX3-2), but the reason is similar to that of sample 1-1 (EX1-1), and a detailed explanation is omitted here. Samples 4-1 (EX4-1) and 4-2 (EX4-2) are similar, but the main difference between them is the timing of contact between the first and second polymers with the lens core. In Sample 4-1 (EX4-1), the lens core is immersed in a buffer containing both the first and second polymers, allowing the first polymer to effectively form an interpenetrating polymer network structure with the surface structure of the lens core, thus affecting the smoothness of the final contact lens surface. The main difference between Sample 5-1 (EX5-1) and Sample 5-2 (EX5-2) is that Sample 5-2 undergoes two sterilization steps. First, it is immersed in Buffer-2 containing PVA and then sterilized once, and then immersed in Buffer-1 containing PVP and then sterilized a second time. Looking at the surface smoothness scores, Sample 5-1 scores higher than Sample 5-2. The reason for this is thought to be that, during the first sterilization of sample 5-2, strong hydrogen bonding and crosslinking reactions first formed between some of the polyvinyl alcohols in the first polymer, which may prevent the second polymer from forming an outer layer together with the first polymer during the second sterilization. As a result, the outer layer may become unstable, potentially leading to a lower surface smoothness score.Comparing sample 9-1 (EX9-1) and sample 6-2 (EX6-2), sample 9-1 has a higher surface smoothness score because it has undergone sterilization. Samples 4-1 (EX4-1) and 7-2 (EX7-2) are similar, but the main difference is that Buffer-3 in which sample 4-1 is immersed contains not only the second polymer but also the first polymer. This allows the second polymer to stably exist on the surface of the lens core body with the help of the first polymer. Therefore, sample 4-1 has a higher surface smoothness score. Similarly, sample 4-1 (EX4-1) has a higher surface smoothness score than sample 8-2 (EX8-2), but a detailed explanation of this is omitted here. Comparing Sample 4-1 (EX4-1) and Sample 9-2 (EX9-2), Sample 4-1 receives a higher surface smoothness score than Sample 9-2 because the Buffer-3 in which it is immersed contains not only the first polymer but also the second polymer, which helps in the formation of an outer layer that improves the smoothness of the contact lens surface.

[0062] Contact lenses from samples 4-1 and 7-2 were rinsed three times with RO water to remove components that can be removed by RO water (including buffer salts NaCl, NaH2PO4, and Na2HPO4) from the surface of the contact lenses. The contact lenses were then dried at 105°C for at least 8 hours to remove moisture and obtain dry lenses. The surface components of the dry lenses were then analyzed using the elemental analysis function of a scanning electron microscope (Energy-dispersive X-ray spectroscopy with Scanning Electron Microscope, SEM-EDX). Elemental analysis data showed that the surface of the dried lens from sample 4-1 contained 4.39% nitrogen, indicating that the secondary polymer (PVP) remained stable on the surface of the lens core even after rinsing with RO water. However, no nitrogen was detected on the surface of the dried lens from sample 7-2, indicating that the secondary polymer (PVP) originally present on the surface of the lens core was washed away after rinsing with RO water. Therefore, by using the SEM-EDX analysis method, it can be further explained that the lens core body of the contact lens in one embodiment of the present invention is covered with an outer shell layer containing a second polymer (PVP).

[0063] Based on the data analysis and explanation described above, it can be demonstrated that the technical features proposed by the present invention can effectively provide contact lenses with an appropriate surface smoothness, thereby improving comfort during contact lens wear.

[0064] Although the present invention has been disclosed above using examples, the present invention is not limited thereto. Those skilled in the art can make several modifications without departing from the spirit of the invention. Accordingly, the scope of protection of the present invention is limited by the appended claims. [Explanation of Symbols]

[0065] 100: Contact lenses 110: Lens core body 120: Outer layer 121: First Polymer 122: Second Polymer

Claims

1. The lens core comprises a lens core body and an outer shell layer covering the lens core body, wherein the outer shell layer contains a first polymer containing polyvinyl alcohol and a second polymer containing polyvinylpyrrolidone, and the first polymer is partially hydrolyzed polyvinyl alcohol with a degree of hydrolysis of 70% to 99%. The second polymer is a copolymer containing polyvinylpyrrolidone, and the copolymer containing polyvinylpyrrolidone is a copolymer of vinylpyrrolidone and dimethylaminoethyl methacrylate. A contact lens characterized by the following features.

2. The contact lens according to claim 1, characterized in that the first polymer covers the lens core body and the second polymer covers the first polymer.

3. The contact lens according to claim 1, wherein the first polymer is a partially hydrolyzed polyvinyl alcohol with a degree of hydrolysis of 80% to 98%.

4. The contact lens according to claim 1, wherein the first polymer is a partially hydrolyzed polyvinyl alcohol with a degree of hydrolysis of 88% to 95%.

5. The contact lens according to claim 1, wherein the molecular weight of the second polymer is 8,000 Da or more.

6. The contact lens according to claim 1, wherein the molecular weight of the second polymer is 160,000 Da or more.

7. The contact lens according to claim 1, wherein the molecular weight of the second polymer is 360,000 Da or more.

8. The contact lens according to claim 1, wherein the molecular weight of the second polymer is 100,000 Da or more.

9. The contact lens according to claim 1, wherein the contact lens is a hydrogel contact lens.

10. The contact lens according to claim 1, wherein the contact lens is a silicone hydrogel contact lens.

11. The contact lens according to claim 1, characterized in that the contact lens can detect the element nitrogen by elemental analysis using a scanning electron microscope, and the element nitrogen originates from the outer shell layer.

Images